Washington, March 14 (IANS): Valacyclovir, a drug commonly used to treat genital herpes, may help reduce the levels of HIV, the virus that causes AIDS, even when patients do not have herpes, a study has suggested.

"These findings are very encouraging," said senior study author Leonid Margolis, head of the Section on Intercellular Interactions at the National Institute of Child Health and Human Development (NICHD), part of the US National Institutes of Health.

"If Valacyclovir's effectiveness against HIV can be confirmed in a larger cohort, it could be added to the mix of drugs used to suppress the virus, and might prove especially helpful in cases in which HIV has developed resistance to other drugs," Xinhua news agency quoted Margolis as saying on Friday.

The study, published online in the British journal Clinical Infectious Diseases, was conducted by researchers from the NICHD, Case Western Reserve University, Emory University and the Civic Association for Health and Education in Peru.

Earlier studies have shown that Valacyclovir reduces HIV levels in patients co-infected with HIV and herpes simplex virus 2 (HSV-2), the virus that causes genital herpes.

Previously, this effect has been attributed to the drug's anti-HSV-2 activity, which then results in fewer active immune cells for HIV to infect.

Yet, the new study indicated that the drug likely reduced HIV levels by interfering directly with HIV's reproductive machinery and did not require the presence of HSV-2.

According to the researchers, HSV-2 chemically alters Valacyclovir, by attaching chemical groups known as phosphates to it, resulting in an altered form of the drug that suppresses HSV-2.

They believed that this form also interferes with HIV's ability to reproduce.

In the new study, researchers enrolled 18 HIV-infected patients, none of whom were infected with HSV-2, and treated them with Valacyclovir.

Half of the patients took Valacyclovir twice a day for 12 weeks, while the other half received a placebo. After two weeks, the placebo group received Valacyclovir while the group originally treated with the drug switched to the placebo.

When the patients took Valacyclovir, their blood HIV levels declined significantly, and when they took the placebo, their HIV levels went up.

Given the ability of the drug to lower HIV levels, the researchers believed that Valacyclovir could one day be added to the cocktail of drugs given to HIV-infected people.